The technology of Carrier Aggregation (CA) has been introduced to a Long Term Evolution-Advanced (LTE-A) system so that a plurality of consecutive or inconsecutive carriers served by the same evolved Node B (eNB) are aggregated together to serve a User Equipment (UE) concurrently.
Uplink Control Information (UCI) includes Acknowledgement/Non-Acknowledgement (ACK/NACK) information, periodic Channel State Information (CSI) and Scheduling Request (SR) information.
The periodic CSI includes Rank Indicator (RI) information, Channel Quality Indicator (CQI) information, Precoding Matrix Indicator (PMI) information and Precoder Type Indication (PTI) information.
In the LTE-A CA system, the Physical Uplink Control Channel (PUCCH) format 3 is defined for transmission of multi-bit ACK/NACK information of a plurality of aggregated carriers. The maximum transmission capacity of the PUCCH format 3 is 22 bits and can support jointly encoded transmission of at most 20 bits of ACK/NACK and a 1-bit SR.
In the Rel-10 system, concurrent transmission of the ACK/NACK information of a plurality of carriers and periodic CSI on a PUCCH is not supported, and if there are both the ACK/NACK of a plurality of carriers and periodic CSI in a current subframe, then only the ACK/NACK is transmitted on the PUCCH whereas the CSI is dropped.
For a UE transmitting ACK/NACK using the PUCCH format 3, only when a support for concurrent transmission of ACK/NACK and CSI in a subframe is configured and one downlink subframe is received only on a Primary Component Carrier (PCC), concurrent transmission of ACK/NACK and periodic CSI of one carrier in the PUCCH format 2/2a/2b in the downlink subframe is supported. If there are a plurality of carriers for which CSI needs to be fed back concurrently in a current subframe, then the CSI of one carrier with high CSI reporting type priority is selected to be reported according to predefined CSI reporting type priorities, where the highest priority reporting types are the types 3, 5, 6 and 2a, the second highest priority reporting types are the types 2, 2b, 2c and 4, and the lowest priority reporting types are the types 1 and 1a, and CSI report contents and bits corresponding to each CSI reporting type in different reporting modes are as depicted in Table 1, and only one reporting type of each activated carrier of the UE is reported in one uplink subframe according to currently configured reporting types and a particular state. If there are a plurality of carriers with the same reporting type priority, then CSI of one of the carriers with the lowest index is further selected to be reported according to indexes of the carriers.
TABLE 1CSI report contents and bits corresponding to CSI reporting types in different reporting modesReporting ModesModeModeModeModeReportingReport1-12-11-02-0TypecontentsMode state(bits/BP)(bits/BP)(bits/BP)(bits/BP)1Sub-bandRI = 1NA4 + LNA4 + LCQIRI > 1NA7 + LNA4 + L 1aSub-band8 antenna ports RI = 1NA8 + LNANACQI/8 antenna ports 1 < RI < 5NA9 + LNANAsecond PMI8 antenna ports RI > 4NA7 + LNANA2Wideband2 antenna ports RI = 166NANACQI/PMI4 antenna ports RI = 188NANA2 antenna ports RI > 188NANA4 antenna ports RI > 111 11 NANA 2aWideband8 antenna ports RI < 3NA4NANAfirst PMI8 antenna ports 2 < RI < 8NA2NANA8 antenna ports RI = 8NA0NANA 2bWideband8 antenna ports RI = 188NANACQI/8 antenna ports 1 < RI < 411 11 NANAsecond8 antenna ports RI = 410 10 NANAPMI8 antenna ports RI > 477NANA 2cWideband8 antenna ports RI = 18NANANACQI/first8 antenna ports 1 < RI ≦ 411 NANANAPMI/second8 antenna ports 4 < RI ≦ 79NANANAPMI8 antenna ports RI = 87NANANA3RI2/4 antenna ports,11112-layer spatialmultiplexing8 antenna ports, 2-layer1NANANAspatial multiplexing4 antenna ports, 4-layer2222spatial multiplexing8 antenna ports, 4-layer2NANANAspatial multiplexing8-layer spatial3NANANAmultiplexing4WidebandRI = 1 or RI > 1NANA44CQI5RI/first8 antenna ports, 2-layer4NANANAPMIspatial multiplexing8 antenna ports, 4 and58-layer spatialmultiplexing6RI/PTI8 antenna ports, 2-layerNA2NANAspatial multiplexing8 antenna ports, 4-layerNA3NANAspatial multiplexing8 antenna ports, 8-layerNA4NANAspatial multiplexing
For Table 1, it shall be noted that:
The bits/BP represents the number of report bits per Bandwidth Part; the CQI/PMI is categorized as a Wideband CQI/PMI and a sub-band CQI/PMI; the antenna ports represent antenna ports; the layer represents a transmission layer; the spatial multiplexing represents spatial multiplexing; the NA indicates that the reporting type is not supported in a corresponding report mode; and L represents the label of a selected sub-band in at most 2 bits.
In the LTE-A Rel-11 CA system, enhanced transmission of Uplink Control Information (UCI) has been investigated, and in order to avoid an influence on downlink scheduling by an eNB due to excessively CSI dropping, concurrent transmission of ACK/NACK of multiple carriers and periodic CSI of one carrier using the PUCCH format 3 is supported, and when there is an SR, concurrent transmission thereof with a 1-bit SR can be further supported.